Non-destructive evaluation of residual compressive strength of post-heated reinforced concrete columns

作者：Yaqub M^*; Bailey C G

来源：Construction and Building Materials, 2016, 120: 482-493.

DOI：10.1016/j.conbuildmat.2016.05.022

• Columns
• Concrete
• Residual compressive strength
• Temperature
• Ultrasonic tests

An experimental study was carried out to evaluate the residual compressive strength of post-heated reinforced concrete columns using techniques applicable in the field. A total of thirty-five reinforced concrete columns (along with three standard cubes for each column) were tested. Ultrasonic pulse velocity tests were carried out on un-damaged and heat damaged reinforced concrete columns and on the related un-damaged and heat damaged concrete cubes. The reinforced concrete columns (fourteen square and thirteen circular) along with three cubes for each column were heated to a uniform temperature of 500 degrees C at a rate of 150 degrees C/h. In addition, fifteen undamaged and fifteen heat damaged extra cubes cast from the same batches of concrete (used for casting the columns) were also tested in order to develop a relationship between pulse velocity tests and the residual compressive strength when the cubes were heated over a temperature range. The fifteen heat-damaged cubes were heated with the same heating rate as that used for the columns to uniform temperatures of 200 degrees C, 300 degrees C, 450 degrees C, 500 degrees C or 550 degrees C. It was shown that the residual compressive strength of concrete on the 7th day of cooling at ambient temperature after exposing to 200 degrees C, 300 degrees C, 450 degrees C, 500 degrees C and 550 degrees C was found to be 80%, 76%, 60%, 47% and 30% of the original un-heated strength respectively. A general relationship was developed between the ultrasonic pulse velocity and the residual compressive strength of cubes over a temperature range of 20 degrees C-550 degrees C in order to relate the compressive strength of cubes directly to the in-situ compressive strength of concrete in the reinforced concrete post-heated columns. Additionally, the theoretical and experimental tested values of the axial compressive strength of un-damaged and heat damaged columns were compared in order to evaluate the residual compressive strength of columns. It was found that the theoretical and tested values agreed well for un-damaged (20 degrees C) and heat damaged (500 degrees C) square and circular columns.

• 出版日期2016-9-1